1. Field of the Invention
The invention relates to a monitoring device for a fuel injection quantity control device.
2. Description of Related Art
In an engine that is mounted in a vehicle or the like, a fuel injection quantity control for engine output adjustment is performed through a fuel injection quantity control device. This fuel injection quantity control device is provided with an injector that injects a fuel supplied to the engine and a control unit that drives the injector. The fuel injection quantity control device calculates an injection quantity command value as the amount of the fuel required to be injected from the injector in one engine cycle based on an engine operation state and performs the injection of the fuel equivalent in amount to the injection quantity command value by energization of the injector. With regard to the execution of the fuel injection equivalent in amount to the injection quantity command value, it is conceivable that the fuel injection is performed by being divided into a main injection and a sub injection (pilot injection, after-injection, and the like) that is a fuel injection smaller in amount than the main injection.
Japanese Patent Application Publication No. 2013-238203 discloses a monitoring device that monitors the presence or absence of an abnormality of the fuel injection quantity control device. This monitoring device calculates a monitor injection quantity as the amount of the fuel that is actually injected based on an energization time monitor value of the injector for each fuel injection and determines the presence or absence of the abnormality of the fuel injection quantity control device based on a comparison between a total value of the monitor injection quantities after the one cycle of the engine and the injection quantity command value. In other words, the fuel injection quantity control device is determined to be abnormal when the total value of the monitor injection quantities and the injection quantity command value significantly diverge from each other. In some cases, a correction that is equivalent to a predetermined correction amount is added to each of the amount of the fuel injected by the main injection and the amount of the fuel injected by the sub injection, examples of the correction including a correction for removing a deviation of the fuel injection quantity from an appropriate value which is attributable to an individual difference between the injectors. In this case, the correction amount is removed from the monitor injection quantity that is calculated for each fuel injection, and then the total value of the monitor injection quantities in one engine cycle is calculated. Then, the total value and the injection quantity command value are compared to each other.